Analysis of soil compaction under different wheel applications using a dynamical cone penetrometer

Rania MAJDOUBI, Lhoussaine MASMOUDI, Abderahmane ELHARIF

Journal of Terramechanics, Volume 111, 2024, Pages 21-30, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2023.09.001.(https://www.sciencedirect.com/science/article/pii/S0022489823000824)

Abstract: Soil compaction is one of the major problems in modern agriculture. Thus, the workability of a soil reflects to its ability to accept the traffic of agricultural machinery and implements. Water content and compaction are factors that influence the rheological behavior of the soil. the representation of soil shows limitations regarding the behavior of the tire-soil interface and its resistance to deformation is both influenced by the different forms of loading application along a tire path on a soil particle. This paper presents a study of the impact of multiple wheel passage, the wheel velocity, and the weight applied to the wheel on the agricultural soil represented by the cone index. To do this, we were inspired to launch an investigation for soil compaction determination at three levels of wheel load, three levels of velocity and at tillage, first, second and third passages of wheel with three replications on clayey sandy mixed grain soil. The results of this study shows that the greatest soil compaction occurred at the highest wheel load (1000 N), the lowest speed (0.1 m/s) and the highest number of passes (third pass), this leads to minimize multiple passes and or follow the same path, also, keeping the load on the ground as low as possible (weight of the machines), and working at high speed in agricultural fields.

Keywords: Soil compaction; Modern agriculture; Off-road equipment; Tire-soil interface; Multiple wheel passage; Rotation speed; Weight applied; Cone index

A terramechanics model for high slip angle and skid with prediction of wheel-soil interaction geometry

Catherine Pavlov, Aaron M. Johnson

Journal of Terramechanics, Volume 111, 2024, Pages 9-19, ISSN 0022-4898,

https://doi.org/10.1016/j.jterra.2023.08.004.(https://www.sciencedirect.com/science/article/pii/S0022489823000691)

Abstract: Previously developed terramechanics models of wheel-soil interaction forces do not cover the full span of possible wheel states, including large slip angles and ratios. This paper synthesizes a model that covers the full range of slip and skid ratios and slip angles by building on classic terramechanics and soil failure models. The need for wheel and soil specific tuning is reduced through use of a closed-form model of soil flow around the wheel to determine the wheel-soil contact geometry. The terramechanics model is validated both with and without the soil flow model on two wheels in sand for slip ratios from −1 to 0.9 and slip angles from 0° to 60°, showing good prediction of tractive forces, sidewall forces, and sinkage over a wide variety of states. The data from these experiments is also presented, as the only open source data set to cover both a high range of slip angles and slip ratios.

Keywords: Terramechanics model; Slip angle; Skid sinkage; Slip sinkage; Planetary exploration rovers; Wheel-soil interaction; Soil flow model

An analytical model for stress estimation at the soil-tire interface using the dynamic contact length

Behzad Golanbari, Aref Mardani

Journal of Terramechanics, Volume 111, 2024, Pages 1-7, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2023.08.006.(https://www.sciencedirect.com/science/article/pii/S002248982300071X)

Abstract: The interaction between soil and tire is a complex phenomenon influenced by various factors, such as soil properties, vertical load on the wheel, and tire characteristics. However, estimating stress at the tire-soil interface is a challenging task due to the unpredictable nature of soil. Existing models for investigating the wheel-soil interaction are based on soil mechanical parameters, which are highly variable and require significant time and resources to measure accurately. In contrast, the amount of wheel sinkage into the soil can be measured in real-time and is derived from the mechanical properties of the soil. Therefore, there is a need to establish a relationship between stress and wheel characteristics such as dynamic contact length and tire sinkage in soil. To address this issue, this study introduces an analytical method to estimate the dynamic contact surface between the tire and soil. A mathematical model is then proposed to estimate stress, assuming the contact surface and variable pressure at the interface between the soil and tire. The stress model is validated through experimental tests conducted at three different vertical load levels and four different wheel traffic levels in the soil bin, repeated three times.

Keywords: Stress; Dynamic contact length; Soil-tire interaction; Analytical model

Research on drag reduction performance of sliding plate of rice direct seeding machine based on non-smooth structure of loach surface

Hongchang Wang, Kaiquan Ding, Guozhong Zhang, Zhen Jiang, Abouelnadar El. Salem, Yuan Gao

Journal of Terramechanics, Volume 110, 2023, Pages 79-85, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2023.08.008.(https://www.sciencedirect.com/science/article/pii/S0022489823000733)

Abstract: Sliding plate has the problems of large sliding resistance and serious soil adhesion. Loach moves freely and flexibly in mud, has highly efficient lubrication and drag reduction effects. The sliding plate of rice direct seeding machine was selected as the research object and loach as the bionic prototype. The macroscopic and microscopic structure characteristics of loach were observed, the body surface of loach was covered by scales, which had a ridged non-smooth structure. The simulation analysis of the drag reduction performance of the non-smooth structure was carried out, the maximum drag reduction rate was 2.55% at the speed of 1 m/s. A bionic sliding plate of rice direct-seeding machine was constructed based on the non-smooth structure of loach body surface, and its working performance was simulated and analyzed. The results of orthogonal test show that the order of primary and secondary factors of bionic structure parameters affecting drag reduction rate was ribbed spacing > ribbed width > ribbed height. The optimal parameter combination was ribbing height 4 mm, ribbing width 4.5 mm, ribbing spacing, and the optimal drag reduction rate was 4.21%. The results of this study can provide theoretical support for bionic design of soil-engaging components in wet and soft paddy field.

Keywords: Loach; Non-smooth; Sliding plate; Drag reduction; Paddy field

Modelling and experimental identification of spring-damping properties of the off-road vehicle rubber tracks, rubber belts, and rubber-bushed tracks subjected to flexural vibrations

Jakub Chołodowski

Journal of Terramechanics, Volume 110, 2023, Pages 101-122, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2023.08.007.(https://www.sciencedirect.com/science/article/pii/S0022489823000721)

Abstract: In the article, a model for predicting the energy losses caused by the flexural vibrations of rubber tracks, rubber belts, and rubber-bushed metal link-tracks for off-road vehicles is proposed, and a test stand and an experimental procedure are developed to identify the mechanical parameters of this model. The track or belt is represented by a chain of discrete rigid links connected by revolute joints, and a discrete spring-element is placed in parallel with multiple Maxwell-elements in each joint to capture the flexural rigidity and damping of the real track or belt. The mechanical parameters of the joint are found by testing real tracks or belts under cyclic bending. The models consisting of three, four, or five Maxwell-elements per joint are the most successful in predicting the response of a sample rubber track to cyclic bending. The spring-damping properties of tracks and belts identified with the method discussed herein can be applied in simulation studies on the interaction of tracked vehicles and soil. Furthermore, vehicle elements such as rubber bushings for suspension systems, rubber torsion springs, and oil-filled and rubber torsion dampers can be tested with this method to find their spring-damping properties required by vehicle dynamics simulations.

Keywords: Rubber belt; Rubber track; Rubber-bushed track; Flexural rigidity; Structural damping; Experimental test; Track system; Tracked undercarriage; Flexural vibrations; Energy dissipation

Push-pull locomotion: Increasing travel velocity in loose regolith via induced wheel slip

Cyndia Cao, Deaho Moon, Colin Creager, Dennis K. Lieu, Hannah S. Stuart

Journal of Terramechanics, Volume 110, 2023, Pages 87-99, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2023.08.005.(https://www.sciencedirect.com/science/article/pii/S0022489823000708)

Abstract: Push–pull locomotion is an effective mobility mode for traversing loose lunar regolith and climbing sandy slopes. A rover with an active suspension can generate thrust from a set of anchored wheels by adjusting its wheelbase while driving the remaining wheels. This paper explores the relationship between the velocities of the rotational and translational suspension elements. Using a kinematic slip greater than 30%–40%, inchworming surpasses both the travel velocity and power efficiency of normal driving on slopes between 10°–20°. On a 20°slope, inchworming improves travel reduction from 98% to 85% and reduces normalized power consumption by a factor of eight. Experiments with NASA’s upcoming Volatiles Investigating Polar Exploration Rover show that increasing kinematic slip increases its travel velocity in a sink tank by 35%. Models using granular resistive force theory indicate that wheels driving at higher slip can generate greater tractive force and thus reduce the load on the anchored wheels. Otherwise, at lower driving slip, the load capacity of anchored wheels may be exceeded and result in oscillatory overall travel. These experiments suggest that there is further room to improve wheeled locomotion by intentionally inducing wheel slip, especially in articulated suspensions.

Keywords: Planetary rover; Slip control; Granular resistive force theory; Push–pull locomotion; Sandy slopes

A photoelastic method for stress analysis of granular terrain beneath a wheel

Yuto Yoshida, Hikari Sakada, Sota Yuasa, Kenji Nagaoka

Journal of Terramechanics, Volume 110, 2023, Pages 69-78, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2023.08.003.(https://www.sciencedirect.com/science/article/pii/S002248982300068X)

Abstract: This paper presents a photoelastic method for the stress analyses of granular terrains beneath a traveling wheel. Recently, wheel terramechanics have been studied using various advanced techniques such as particle velocimetry and machine learning. However, the dynamic profiles of the stress distributions in soil have not been directly observed. In this paper, we propose a photoelastic method to experimentally demonstrate the two-dimensional stress analysis of a granular terrain. This method uses photoelastic disks as terrain particles; thus, the internal stress and propagation of the granular terrain can be visualized using the interference fringe of light. This study aimed to observe the dynamic behavior of grains, typically simulating circular or spherical objects of the granular terrain. To demonstrate the photoelastic method for simulated ground, we developed a single-wheel testbed using photoelastic materials. Moreover, the effects of mixing with non-photoelastic materials were investigated to simulate steady states with small and large wheel-slip conditions. This paper presents a force chain analysis of the photoelastic particles beneath a single traveling wheel. The force chain structure was geometrically compared with the propagation angle and length. In addition, the orientational orders of the force chains were quantitatively evaluated under both small and large wheel slip conditions. The experimental results confirmed that the photoelastic method can reveal dynamic changes in the internal stress structures of granular terrain beneath the wheel under various slip conditions.

Keywords: Photoelastic method; Stress propagation of granular terrain; Force chain analysis; Orientational order

Coupled nonlinear controller for vehicle trajectory tracking in a deformable soil: Application to a four-wheeled mobile agricultural robot

Rania Majdoubi, Lhoussaine Masmoudi, Abderrahmane Elharif

Journal of Terramechanics, Volume 110, 2023, Pages 47-68, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2023.08.001.(https://www.sciencedirect.com/science/article/pii/S0022489823000666)

Abstract: In this paper, the coupled longitudinal and lateral control of the mobile agricultural robot “Agri-Eco-Robot’’ is addressed. As a first step, the Newton's law is used to develop the dynamical modeling of the mobile agricultural robot. The wheel-ground contact is modeled using the Terramechanics law called Extended-Bekker. The validation of the developed vehicle model was then conducted using an automotive simulator. The developed vehicle model is then used to derive the coupled control laws for the lateral and the longitudinal vehicle dynamics. The proposed controller is realized using two overlapping controllers, the first is dealing with coupled control of longitudinal and lateral dynamics to command the traction, and the second is the controller that minimize slipping, both are developed using the Lyapunov's theory. This controller is compared with the dynamics where the slip ratio is not controlled according to two scenarios in which one is the heigh velocity and the other is low velocity, this control law is validated using an automotive simulator applied to the mobile robot ‘Agri-Eco-Robot’. The result of this control law shows the necessity of the slipping control when navigating in a rough environment such as agricultural fields, assuming a low-speed command to ensure system stability.

Keywords: Combined controller; Mobile agricultural robots; Navigation in a rough environment; Dynamic model; Terramechanics law; Trajectory control law; Traction; Slip ratio; Lyapunov's control; Heigh velocity; Low velocity

Optimization of grouser shape ratio for coastal terrain driving device using discrete element method

Ji-Tae Kim, Hyuek-Jin Choi, Jae-Won Oh, Young-Jun Park

Journal of Terramechanics, Volume 110, 2023, Pages 27-37, ISSN 0022-4898

https://doi.org/10.1016/j.jterra.2023.07.004.\(https://www.sciencedirect.com/science/article/pii/S0022489823000575)

Abstract: Using the discrete element method (DEM), this study derived the optimal shape ratio of a grouser driving in a coastal terrain. To develop a DEM model that considers the properties of the coastal terrain, experiments were performed on the physical and mechanical properties of the terrain, and parameters of the DEM model were calibrated using the experimental results. In addition, a terramechanical experiment was performed to validate the DEM model, for which parameters were calibrated. Furthermore, simulations were performed on the change in thrust according to the existence or nonexistence of the grouser and the change in thrust and sinkage according to the shape ratio using the validated DEM model. Consequently, the track with grouser generated a larger thrust than that without the grouser. Thus, the optimal shape ratio range of coastal terrain was derived using the DEM model, considering the mechanical properties of the terrain.

Keywords: Discrete element method (DEM); Coastal terrain; Terramechanics; Grouser optimization; Driving performance